Question

A 12,500 kg railroad freight car travels on a level track at a speed of 5.2 m/s. It collides and couples with a 22,600 kg second car, initially at rest and with brakes released. What is the speed of the two cars after collision

Answer 1

Given :

A 12,500 kg railroad freight car travels on a level track at a speed of 5.2 m/s.

It collides and couples with a 22,600 kg second car, initially at rest and with brakes released.

To Find :

The speed of the two cars after collision.

Solution :

It is given that car couples with each other. So speed of both the cars after collision is same. Let, it be v.

Applying conservation of momentum, we get :

$m_1u_1 + m_2u_2 = (m_1 + m_2 )v\\\\12500\times 5.2 + 22600\times 0 = ( 35100)v\\\\35100v = 65000\\\\v = 1.85\ m/s$

Therefore, the speed of the two cars after collision is 1.85 m/s.